Rotatable and extendable locking shaft apparatus

ABSTRACT

An adjustable locking shaft apparatus is disclosed. A locking adjustment system, fully enclosed within the movable shaft segments enables rapid simultaneous angular and length adjustments to be made to the shaft. An eccentric cam configuration operated by simple twisting of the shaft segments provides the locking pressure for maintaining selected adjustments. The apparatus provides an infinite number of adjustment positions. A kayak paddle implementation of the invention is disclosed.

FIELD OF THE INVENTION

This invention relates generally to apparatus for extending and positioning support legs, shafts, or handles, and particularly to an improved handle configuration for kayak and canoe paddles.

BACKGROUND OF THE INVENTION

There are a number of applications where it is desirable to have an extendable shaft or handle that can extend to varied lengths and/or be rotatable to various rotational orientations. It is also often advantageous for such device to easily retract or disassemble for storage or transport in relatively compact configuration. Typically, such handles or shafts involve a plurality of cooperatively telescoping tubular members with various types of internally or externally threaded locking members for selectively fixing the longitudinal and rotational orientation of the tubular members relative to one another. The needs for such structures are wide spread, and include such things as tripod legs for cameras, survey equipment and the like, paint roller handles, ceiling light bulb changers, roof snow rakes, lawn and patio furniture umbrellas, tree branch pruning and trimming implements, golf ball retrievers and recreational implements such as paddles for kayaks and canoes.

For many such applications, it is permissible to have such extendable members lock at predetermined fixed longitudinal and angular positions relative to one another so as to provide handles of predetermined fixed lengths or rotational orientations. Length adjustment by fixed lengths is adequate for many applications such as for patio furniture umbrellas. However, in certain applications it is desirable or critical that the shaft or handle length be infinitely adjustable to fit the particular application or to match the unique size or ability requirements of the user. This also is true for the angular adjustability of the telescoping handle portions of the device. In applications where the adjustable handle is attached to a single implement at only one end of the handle, the relative angular positions of the telescoping handle segments are typically not important, since the handle, once locked in extended position, can simply thereafter be rotated by the user to appropriately position the implement attached to it to the desired rotational position required to perform the implement function. For example, the relative angular positioning of handle extensions for light bulb changers or paint rollers in general, are not critical.

For two-ended implement devices such as kayak paddles, however, it is desirable to have a handle configuration that is continuously or infinitely adjustable in both length and relative angular position between the handle segments. For example, the length can be maximally adjusted to the size of its user and the angles of the paddle blades relative to one another on opposite sides of the handle can be adjusted to maximize response to real-time paddling conditions being experienced. Such paddle adjustment capabilities also allow a single paddle to accommodate multiple users under varying paddling conditions. It is also desirable that each kayak paddle be rapidly adjustable by the user while he/she is paddling the kayak, to accommodate changing water or wind conditions or speed requirements, without requiring the user to remove his/her hands from the paddle to make the adjustments. The paddler should preferably be able to make any adjustments on-the-fly, while continuing to paddle, or if necessary, by missing a minimum number of strokes.

Durability, ruggedness, reliability, simplicity and operability of the adjustment apparatus under severe environmental conditions are also important. This is particularly true for apparatus that would be subjected to gritty materials such as dirt, sand or dust, or to corrosive materials such as salt water, chlorine or the like. Preferably, the adjustable apparatus will be relatively immune to such environmental conditions and to human abuse during use and transport, while having the strength and durability to handle the forces imparted to it during normal use without altering the length and/or angular adjustment settings.

While the invention applies to many tools and implements, it will primarily be described herein with respect to its applicability to a kayak paddle, which represents one of the most demanding use and environmental applications for an implement employing the invention.

Adjustable kayak paddle handles are known in the art. One type of paddle, for example manufactured by Epic Kayaks, Inc., has a two-piece handle that rotates to adjust the relative blade angles. The blade angle is set by pressing a spring biased button on the shaft and by rotating the shaft pieces relative to one another until the button snaps into a desired one of a plurality of circumferentially spaced holes on the shaft. This configuration does not allow for handle length adjustment and permits blade angle adjustment only at discreet pre-determined angles. The adjustment feature is susceptible to environmental damage and introduces looseness or play between the handle segments. Further, the handle cannot be readily adjusted while the paddle is in inoperative use, and has a natural weakness where the angle setting holes have been drilled through the shaft.

Kayak handle configurations that allow both length and angular adjustments are manufactured by Epic Kayaks, Inc. under its trademark Length Lock™ and by Simon River Sports under its E-Z Set™ mark. These paddle constructions use telescoping handle portions that are slidable relative to one another to adjust the handle length and relative blade angles. The outer handle tube is threaded adjacent its edge and is circumferentially slotted to form a plurality of moveable compression fingers that slidably engage the inner handle segment. A compression nut threads onto the outer handle threads, and when tightened, radially engages and applies pressure to the fingers, which frictionally grip the underlying shaft segment to lock it in place relative to the outer shaft segment. These handle configurations allow for both handle length and blade angle adjustment. However, the threaded structure is exposed to the environment and is therefore highly susceptible to damage from dirt and sand, and requires lubricants and frequent cleaning for efficient and reliable operation.

What is lacking in the art is a shaft configuration, particularly useful with kayak paddles, that rapidly provides for both length and angular adjustment and that is highly tolerant to rugged environmental and operative use conditions. The present invention addresses these needs.

SUMMARY OF THE INVENTION

This invention provides a simple yet reliable and efficient locking adjustment system for rapidly adjusting the length and angular relationship between the segments of shaft or handle members. While particularly suitable for use with kayak or canoe paddles for adjusting the shaft length and blade feather angles, the invention can be applied to a wide range of products and applications including, for example, handle, leg and shaft members which require rapid or accurate length adjustment or angular adjustments.

The locking adjustment system of this invention is self-contained within the inner cavities of the shaft segments with which it is used, which protects it from harmful environmental elements. The locking adjustment system has no external or loose parts required for its operation. This provides the shaft segments with a clean, smooth look and feel. The user simply grasps the handle elements requiring adjustments and slightly turns or twists them relative to one another to engage and release the locking system. This can be done while a person is using the shaft for its intended purpose.

An eccentrically configured cam and rotatable interlock ring member cooperatively move with the shaft segments being adjusted to selectively release (loosen) or lock the shaft segments at the desired length and/or angular positions. The shaft segments protect the locking assembly and form a unified stable shaft member when locked.

According to one aspect of the invention, there is provided a workpiece connected to an adjustable shaft apparatus having: (a) a first hollow shaft portion; (b) a second hollow shaft portion configured for axial operative alignment with the first shaft; and (c) a releasable locking assembly mounted within and connecting the first and second shafts in axial alignment wherein the locking assembly is arranged and configured to respond to relative twisting motion between the first and second shafts about their common axes, to selectively fix the angular orientations of the first and second shafts relative to one another to any desired angular positions. According to a further aspect of the invention, the releasable locking assembly is configured in a manner such that it contains no threaded operative parts. According to a further aspect of the invention, the releasable locking assembly is operable to fixedly lock the first and second shafts together when the shafts are relatively twisted in first angular directions about the axis, and is operable to release the locking condition and to allow free angular relative motion between the first and second shafts when the shafts are relatively twisted in second angular directions, opposite to the first angular directions about the axis. According to a further aspect of the invention, the amount of angular rotation or twisting of the first and second shafts about the axis in order to lock and unlock the shaft positions relative to one another is preferably less than about 180°, even more preferably less than about 90°, and even more preferably yet less than about 45°. The releasable locking assembly is operable not only to adjust the relative angular positions of the shaft segments, but also to provide infinite length adjustments for the composite length of the first and second shafts, within an adjustment length range, by using the same simple twisting locking and releasing motions that are used to lock the relative angular positions of the first and second shafts. A shaft length extension piece may be inserted between the first and second shaft ends that are connected to the releasable locking assembly, or alternatively, one of the shaft pieces may be configured to telescopically slide within the other to form the extension capability.

According to yet a further aspect of the invention, there is provided an adjustable kayak paddle having: (a) a shaft having first and second ends and being separable near its longitudinal center; (b) paddle blades fixedly attachable to the first and second shaft ends; and (c) a releasable locking assembly within the shaft and bridging the separable portion thereof, wherein the locking assembly is operable in response to relative twisting motion between the separable shaft segments about the shaft axis, to fix the angular orientations of the shaft segments and attached paddle blades about the axis. The angular adjustment provides for infinite blade feathering adjustments by a simple twist of the shaft. The releasable locking assembly is further operable to adjust the length of the shaft at any desired length adjustment position within a length adjustment range provided for the paddle.

According to yet another aspect of the invention, there is provided a shaft adjustment locking apparatus of a type that is sized and configured to be entirely operatively inserted within first and second joinable shaft segments to be adjusted relative to one another, and of a type which contain no operable threaded parts. The shaft adjustment includes: (a) a first portion configured for fixed mounting within the first shaft; (b) a second portion configured for slidable movement within and relative to the second shaft. The second portion includes a cam member fixed for movement with the first portion, and a cam follower rotatably mounted on the cam member and engageable with an inner surface of the second shaft for selectively frictionally engaging the inner surface of the second shaft in response to rotation of the cam follower relative to the cam member. The cam member may include a cam surface that is eccentrically oriented in relation to the longitudinal axis of the first and second shafts.

These and other features of the invention will become apparent to those skilled in the art upon a more detailed description of preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the Drawing, wherein like numerals represent like parts throughout the several views:

FIG. 1 is an exploded perspective view of an adjustable handle locking apparatus employing the principles of this invention;

FIG. 2 is a diagrammatic view of a two piece handle incorporating this invention, illustrating the handle portions fixed in abutted longitudinal relationship to one another, providing for minimum shaft length;

FIG. 3 is a diagrammatic view of the two piece handle of FIG. 1, illustrating the handle portions fixed in a first slightly extended longitudinal relationship relative to one another, providing for a longer shaft length than the structure of FIG. 2;

FIG. 4 is a diagrammatic view of the two piece handle of FIG. 2, illustrating the handle portions fixed in a second extended longitudinal relationship to another, providing for a longer shaft length than that of the structure of FIG. 3;

FIG. 5A is a front elevation view of a double paddle configuration incorporating this invention, illustrating the paddle blades as being angularly positioned in the same plane.

FIG. 5B is an end view of the paddle configuration of FIG. 5A;

FIG. 5C is an enlarged view of the central handle portion of the paddle configuration of FIG. 5A, graphically illustrating the angular alignment of the paddle blades;

FIG. 6A is a front elevation view of the double paddle configuration of FIG. 5A, illustrating the paddle blades angularly positioned 30 degrees out of line with one another;

FIG. 6B is an end view of the paddle configuration of FIG. 6A;

FIG. 6C is an enlarged view of the central handle portion of the paddle configuration of FIG. 6A, graphically illustrating the 30 degree angular displacement of the paddle blades;

FIG. 7A is a front elevation view of the double paddle configuration of FIG. 5A, illustrating the paddle blades angularly positioned 60 degrees out of line with one another;

FIG. 7B is an end view of the paddle configuration of FIG. 7A;

FIG. 7C is an enlarged view of the central handle portion of the paddle configuration of FIG. 7A, graphically illustrating the 60 degree angular displacement of the paddle blades;

FIG. 8A is an enlarged top view of the handle locking assembly portion of the handle apparatus of FIG. 1, illustrating the moveable ring thereof as it would be positioned on the eccentric cam in a first position, wherein the handle segments are free to move relative to one another;

FIG. 8B is an end view of the handle locking assembly of FIG. 8A;

FIG. 9A is an enlarged top view of the handle locking assembly portion of the handle apparatus of FIG. 1, illustrating the moveable ring thereof positioned on the eccentric cam in a second position, wherein the handle segments and locking assembly have been moved toward a locking position;

FIG. 9B is an end view of the handle locking assembly of FIG. 9A;

FIG. 10A is an enlarged top view of the handle locking assembly portion of the handle apparatus of FIG. 1, illustrating the moveable ring thereof positioned on the eccentric cam in a third position, wherein the handle segments and locking assembly are fixed in a locked position; and

FIG. 10B is an end view of the handle locking assembly of FIG. 10A.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a simple, yet efficient and highly reliable cam locking apparatus for joining two shaft segments in a manner that allows the two shaft segments to be cooperatively moved by a simple twisting motion of the shaft segments to simultaneously longitudinally extend and/or angularly position the shaft segments relative to one another. The invention applies to any split or telescoping shaft segment structures requiring either longitudinal or angular adjustments to be made between the two shaft segments.

While the invention is applicable to many multiple shaft locking devices, such as to adjustable tripod leg bases, or to extension poles or handles for various implements such as ceiling light changers, or paint roller extension handles, or tree pruning extension handles, or yard umbrella pole extensions, or extending curtain compression rods, and the like—the preferred application for the invention is as a rapid shaft length and blade angle position adjustment mechanism for kayak and canoe paddles. Therefore, the following description of a preferred embodiment of the invention. will illustrate its applicability to kayak paddles. It will be understood, however, that the invention and the claims appended hereto are not to be limited to its use with paddles, but that the invention applies to the positioning and locking of all multiple shaft segment configurations.

The invention provides for infinite length adjustments, within the overall adjustment range for the shafts, and infinite angular adjustments over the 360 degree rotational relative movements of the shaft segments. The term “infinite” refers to the fact that there are no discrete or preset positions at which the adjustments must be secured. Rather, the shafts can be secured at any desirable position along the length of the overall length adjustment range and at any angular position along the 360 degree rotational adjustment range of the shafts. A cam locking apparatus is entirely enclosed and rides within the inner diameter of one of the shaft segments, and is therefore protected from adverse environmental elements such as sand, mud, dirt, grime, salt water and the like. Further, the cam locking apparatus has no threaded parts that are expensive to manufacture and difficult to maintain, particularly when sand or grit gets caught between the threads. The cam locking apparatus of this invention requires no lubrication and can be quickly cleaned if necessary by simply pulling the two shaft segments apart and washing or blowing off the cam locking segments.

While the preferred embodiment of the invention will be described with respect to cooperatively mating cylindrical shaft segments, it will be understood that the inventive concepts would not require the shaft segments to be cylindrical, but that other cross-sectional configurations could be used. Also, while the preferred embodiment examples used to describe the invention will refer to parts made from certain materials, the invention is not to be limited by any particular materials. It will be understood that all alternative materials, sizes, finishes and the like could be used within the broad concepts of this invention. Further, while the preferred embodiment description will describe shafts of hollow, tubular construction, it will be understood that the entire shaft need not be hollow, but only those portions thereof that are required to be hollow in order to accommodate the adjustment apparatus and the relative length and angular adjustment movement ranges of the adjustable shaft assembly.

Referring to FIG. 1, a preferred embodiment of a shaft adjustment locking apparatus is generally illustrated at 10. The shaft adjustment locking apparatus is operable to adjust the relative longitudinal position and the relative angular position of axially aligned shaft segments 12 and 14. For simplicity in describing the invention herein, the shaft segment 12 may be referred to as the “right” or first shaft segment, and the shaft segment 14 may be referred to herein as the “left” or second shaft segment. In the preferred embodiment, first and second shaft segments 12 and 14 have common inner and outer diameters, such that when axially placed end to end, they would appear as a single common shaft. The shaft segments may be configured of any appropriate material. In the preferred embodiment described wherein the shaft segments comprise the shaft of a kayak paddle, such shafts are typically made from aluminum, or composites of materials such as fiberglass, carbon, carbon fiber, or epoxy resin. A tube or ferrule extension 16, generally of the same material as the shaft segments 12, 14, is axially inserted and fixedly secured within the first shaft segment 12. The outer diameter of the ferrule 16 is generally the same as the inner diameter of the first shaft segment 12 so as to provide a cooperative snug fit therebetween. In a preferred embodiment, the shaft segments 12 and 14 and the ferrule tube 16 are made of composite materials, and the ferrule tube 16 is secured by glue within the first shaft segment 12. The inner diameter of the ferrule tube 16 is denoted at D1 in the figures. The longitudinal length LI that the ferrule tube 16 extends beyond the end of the first shaft segment 12 represents the total amount of available longitudinal extension, or extension “range,” of the shaft assembly, which will become more apparent upon a further description f the invention. It will be appreciated that while an extension ferrule has been shown herein to provide the shaft extension function, the two shaft segments 12 and 14 could be made having different diameters so as to telescopically mate with one another, as is well known in the art.

A cam insert member is generally indicated at 20. In the preferred embodiment, the cam insert member is constructed from nylon or polypropylene material. The cam insert member is axially aligned with the first and second shaft segments 12 and 14 and has a first cylindrical extension segment 21 having a diameter sized and configured for insertion within the inner diameter D1 of the tube member 16. The cylindrical extension segment 21 includes a plurality of external rib members 22 longitudinally extending along the outer circumference of first cylindrical extension segment 21 so as to provide a snug mating fit with the inner surface of the tube ferrule extension 16 and to allow glue to be placed around the outer circumference of the extension segment 21 for gluing the extension segment 21 within the tube member 16. The cam insert member 20 further includes a first retaining shoulder member 23, having a first bearing surface 23 a that abuts the first cylindrical extension segment 21 and engages the outer (distal) end of the ferrule tube 16 when the first cylindrical extension segment 21 is secured therein. The first retaining shoulder member 23 also has a second bearing surface 23 b, oppositely disposed from the first bearing surface 23 a. The outer diameter of the first retaining shoulder member 23 is the same or slightly less than the outer diameter of the ferrule tube extension 16, and generally forms an extension thereof when the cam insert member 20 is affixed to the ferrule tube 16.

The cam insert member 20 further has a second cylindrical extension segment 25, the outer surface 25 a of which forms a camming surface, as hereinafter described in more detail. The second cylindrical extension segment 25 extends between the second bearing surface 23 b of the first retaining shoulder member 23 and a first bearing surface 27 a of a second cylindrical retaining shoulder member 27. The second retaining shoulder member 27 further has a second bearing surface 27 b. The second retaining shoulder member 27 is axially aligned with the first and second shaft segments 12 and 14 and has an outer diameter sized slightly smaller than the inner diameter of the second shaft segment 14 so as to cooperatively matingly slide within the inner diameter of the second shaft segment 14. The longitudinal axis 29 of the second cylindrical extension 25 is offset from the longitudinal axis 18 of the shaft segments 12 and 14 such that the camming surface 25 a of the second cylindrical extension segment 25 forms an eccentric camming surface for the cam insert member 20. A stop member 28 radially aligned with the shaft segment axis 18 extends from the outer surface of the second retaining shoulder member 27 and down to the camming surface 25 a of the second cylindrical extension segment 25.

An interlock ring member 32 is sized and configured to longitudinally fit between the bearing surfaces 23 b and 27 a and to rotatably ride upon the camming surface 25 a of the second cylindrical extension segment 25. The interlock ring member 32 has a slot 33 longitudinally extending the length of the ring member 32 and a radially oppositely disposed recessed portion 34 longitudinally extending along the inner wall 35 of the interlock ring member, forming a thinner wall thickness for the ring member along the recessed portion 34. The longitudinal slot, in combination with the thinner wall along the recessed portion 34 of the interlock ring member allows the ring member to be pulled open in the direction of the double arrow E as shown in FIG. 1, to allow the ring member 32 to be mounted in overlying rotatable engagement with the camming surface 25 a of the second cylindrical extension segment 25, without imparting harmful; stress to the interlock ring member material. The interlock ring member 32 has a first end bearing surface 32 a configured for sliding engagement with the second bearing surface 23 b of the first retaining shoulder member, and a second end bearing surface 32 b configured for sliding engagement with the first bearing surface 27 a of the second retaining shoulder member 27. The inner wall 35 of the interlock ring member 32 slidably rotatably bears upon and engages the camming surface 25 a of the second cylindrical extension segment. The length of the interlock ring member 32 between its first and second ends 32 a and 32 b and the inner diameter of the inner wall 35 thereof are cooperatively sized relative to the first and second shoulder members 23 and 27 and the second cylindrical extension segment 25 respectively such that the interlock ring member freely rotates on the camming surface 25 a.

The wall thickness of interlock ring member 32 tapers from a minimum thickness along the recessed portion 34 to its greatest thickness adjacent the longitudinal slot 33. This is shown in end view in FIG. 8B. When the thickest portion of the ring 32 is aligned as in FIG. 8B on that side of the camming surface which lies closest to the shaft central axis 18, the outer surfaces of the interlock ring member 32 will generally align with the outer surface of the shoulder member 27 and the inner diameter of the second shaft segment 14. As the ring 32 begins to move in a clockwise direction as indicated successively in FIGS. 9B and 10B, the thicker wall portion of ring 32 will lie adjacent that portion of the camming surface 25 a with lies furthest from the shaft central axis 18, causing the outer surface of the interlock ring member 32 to radially project outward beyond the outer surface of the shoulder member 27 so as to frictionally lockingly engage the inner surface of the second shaft segment 14. Therefore, the combination of the eccentrically positioned camming surface and the tapered wall thickness of the interlock ring member provide the locking and unlocking action of the adjustment locking apparatus, as will become apparent from the following descriptions.

The interlock ring member 32 has a third end bearing surface 32 c which is longitudinally offset from the second end bearing surface 32 b but on the same end of the interlock ring member 32. First and second stop surfaces 37 a and 37 b extend in the longitudinal direction and interconnect the second and third end bearing surfaces 32 b and 32 c, as illustrated in FIG. 1. When the interlock ring member 32 is operatively engaged with the camming surface 25 a, the third end bearing surface 32 c will slidably engage the distal end of the radial rib stop member 28, and the second end bearing surface 32 b of the interlock ring member 32 will slidably engage the first bearing surface 27 a of the retaining shoulder member 27. The rotational travel of the interlock ring member 32 about the cam axis 29 of the camming surface 25 a will be limited by the radial rib stop member 28 as engaged by the first and second stop surfaces 37 a and 37 b. As viewed from the left side of the figure, looking into the shaft segment axis 18 as it exits the left shaft 14, the clockwise rotation of the interlock ring member 32 will be limited by engagement of the second stop surface 37 b with the rib stop member 28. Conversely, the counterclockwise rotation of ring member 32 will be limited by engagement of the first stop surface 37 a with the rib stop member 28. When so positioned in the fully rotated counterclockwise direction (when first stop surface 37 a engages rib stop member 28), the outer surface of the interlock ring member 32 will be generally axially aligned with the shaft segment axis 18 such that the outer surface of the interlock ring member 32 will form a generally cylindrical extension of the outer surface of the second retaining shoulder member 27, allowing the second retaining shoulder member 27, the interlock ring member 32, the first shoulder member 23 and the ferrule tube extension 16 to freely axially slide within the inner diameter of the left or second shaft segment 14. This rotational orientation and configuration of the interlock ring member is illustrated in FIGS. 8A and 8B.

As the interlock ring member 32 begins to rotate in the clockwise direction (as viewed from the left end of FIG. 1), the eccentric offset orientation of the camming surface 25 a along with the varying thickness of the interlock ring's wall, will cause the outer surface of the interlock ring member 32 to begin extending radially outward beyond the outer surface of the shoulder member 27, as illustrated in FIGS. 9A and 9B. This eccentric camming action will cause the outer surface of the interlock ring member to exert frictional radial pressure against the inner surface of the left shaft segment 14.

Continued rotation of the interlock ring member 32 in the clockwise direction and up to the fully rotated position (wherein first stop surface 37 a engages the rib stop member 28) will cause the interlock ring member to assume its fully cammed and radially projected position, as illustrated in FIGS. 10A and 10B. In operation, the right and left shaft segments 12 and 14 would become fully locked relative to one another somewhere between the interlock ring member 32 positions illustrated in FIGS. 8 and 10.

The shaft adjustment locking apparatus 10 is operated by relative rotational twisting of the right and left shaft segments 12 and 14. When the interlock ring member 32 is positioned as shown in FIG. 8, the shoulder member 27, the ring member 32, the shoulder member 23 and the ferrule tube 16 can be freely longitudinally moved in the shaft segment 14 axial direction such that the first and second shaft segments 12 and 14 can be relatively axially moved with respect to one another. When the desired axial position of the first and second shaft segments is attained, in order to fix or lock that longitudinal position, one needs to merely rotationally twist the right and left shaft segments relative to one another. This is accomplished (with reference to FIG. 1) by rotating the right shaft segment 12 in a counterclockwise direction (as viewed from the left end of FIG. 1), while holding the left shaft segment 14 stationary. As the right shaft segment 12 is rotated, the cam insert member 20 which is fixedly secured thereto also begins to rotate with the right shaft segment 12. As the cam insert member rotates, the eccentrically mounted second cylindrical extension segment 25 will cause its camming surface 25 a to exert radial forces upon the inner surface of the interlock ring member 32. Frictional engagement of the outer surface of the interlock ring member 32 with the inner surface of the left shaft segment 14 will cause the interlock ring member 32 not to rotate with the second cylindrical extension segment 25, but to tend to remain fixed with the left shaft segment 14. As the right shaft segment 12 continues to rotate, the eccentric camming action of the camming surface 25 a exerts significant radial pressure against the interlock ring member 32, which in turn exerts radial pressure against the inner surface of the left shaft segment 14, to effectively prevent further rotational motion of the right shaft segment 12, thus locking the right and left shaft segments 12 and 14 to one another.

To unlock the shaft segments and to thus permit readjustment, the process is simply reversed. The right shaft segment 12 is rotated in the clockwise direction (as viewed from the left in FIG. 1), thereby releasing the eccentric cam surface 25 a pressure from the interlock ring member 32, thereby releasing the pressure exerted by the interlock ring member 32 upon the inner wall of the left shaft segment—unlocking the assembly and permitting the right and left shaft members to be longitudinally moved relative to one another. In the preferred construction of the cam assembly, the tolerances have been selected such that the shaft segments need only be relatively rotated a slight amount, preferably under 180°, more preferably under 90°, and more preferably yet under 45°, in order to lock or release engagement of the shaft segments.

The longitudinal adjustment feature is diagrammatically illustrated in FIGS. 2-4. Assuming that only longitudinal (length) adjustment to the shaft positions is being made, FIG. 2 illustrates the shaft assembly as it would appear in unextended form. In such instance, the ends of the right and left shaft segments 12 and 14 respectively abut one another, and none of the ferrule tube 16 is visible. The boxes 40 and 42 illustrated in FIGS. 2-4 are simply indicia labels, as described in more detail hereinafter. FIG. 3 illustrates the relative positions of the right and left shaft segments 12 and 14 as they would appear when locked in a slightly extended configuration wherein the ferrule tube 16 is visible between the ends of the right and left shaft segments. FIG. 4 illustrates a locked position wherein the right and left shaft segments are significantly spaced from one another. As indicated in FIG. 4, the ferrule tube 16 can be marked in ruler fashion with indicia degradations 44 so as to allow the user to accurately determine the desired length of the shaft.

The shaft adjustment locking apparatus also easily enables angular positions between the right and left shaft segments to be fixed. The same procedure discussed above with respect to locking and unlocking the rotational movement between the right and left shaft segments is employed to set the relative angular positions of the shaft segments. Referring to FIGS. 5C-7C, three rotational shaft positions have been illustrated for the locking mechanism. FIG. 5C illustrates a locked position wherein there is no angular rotational position between the right and left shaft segments 12 and 14. The relative rotational angle feature has significance when the shaft segments are connected to some type of work implement as for example to the blades 51 and 52 of a kayak paddle 50. FIGS. 5A-7A illustrate a kayak paddle having right and left paddle blades 51 and 52 corresponding to the right and left shaft segments 12 and 13 of a kayak paddle handle 53. When the angular rotation of the right and left shaft segments 12, 14 is 0 degrees as shown in FIG. 5C, the paddle blades 51 and 52 of the kayak paddle 50 may be aligned in the same plane, as shown in the end view (FIG. 5B) of the paddle. By releasing the locking apparatus as previously discussed by rotating the right shaft segment in a clockwise direction, the relative angular position of the right and left shaft segments can be adjusted to any desired angular rotation and locked into that position by turning the right shaft segment in the counterclockwise direction. The effect of locking the angular position at a 30 degree angle, as illustrated in FIGS. 6A, 6B and 6C is that the paddle blades 51 and 52 will be rotated (in end view) 30 degrees relative to one another. Similarly, when the relative shaft angular adjustment is set at 60 degrees as illustrated in FIG. 7C, the paddle blades 51 and 52 of the paddle 50 will be angularly rotated (in end view) from one another by 60 degrees. Obviously, while specific marked angular degradations are illustrated in FIGS. 5C, 6C and 7C, the locking adjustment apparatus of this invention allows for infinite angular adjustments between 0 and 360 degrees (the full rotational movement of the shafts segments). Similarly, the shaft adjustment locking apparatus of this invention enables infinite length adjustments to be made between the shaft segments, as allowed by the length of the ferrule tube extension or by the amount of overlapping shaft material available between the shaft segments.

Those skilled in the art will readily appreciate the advantages this invention provides for shaft length and angle adjustment, particularly for kayak paddle design and use. The locking and adjustment mechanisms are entirely self enclosed within the inner cavities of the shaft segments, thus protecting them from environmental damage and requiring no unsightly and in-the-way tightening or adjustment collars on the handle. The locking adjustment system requires no threaded or loose or external parts that are susceptible to damage under severe use or environmental conditions and lead to increased wear and reduced reliability issues. The internal cam feature provides positive solid locking action with no play in the shaft when the system is tightened, yet is easy to loosen for readjustment. The handle can be readily disassembled for storage or transport by a simple twist to loosen the locking cam assembly and by pulling the handle segments apart from one another.

The locking adjustment system allows rapid paddle length and blade feature angle adjustments to be made in infinite positions by simple twisting to loosen and twisting to tighten motions of the handle segments, without requiring the user to take his/her hands off of the handle. Rapid adjustments can be made in mid-stroke.

The ability to rapidly, efficiently and simultaneously adjust the paddle length and feather, provide tremendous benefits to the user. The same paddle can be used to accommodate the needs and abilities of different users who require different lengths or blade feather angles. The same paddle can be shortened for down water paddling or extended for flat water, for narrow single or double touring kayaks, for larger sit on top kayaks or for sea kayaking. The user can fine-tune his blade feather angle to meet existing water, wind or current conditions. These and other features and advantages of the invention will be readily apparent to those skilled in the art, not only for kayaking and paddle applications, but for other shaft extension adjustment and locking applications.

While the invention has been described with respect to a preferred embodiment application for kayak paddles, and with respect to specific types of components and materials used therein, it will be understood by those skilled in the art that the invention is not to be limited in any manner by the specifics of the described embodiments, materials, component sizes or operative parameter values which have been described only to indicate a clear example of how the principles of the invention can be specifically applied to shaft adjustment and locking systems. All alternatives and modifications of the foregoing are intended to be covered within the broad scope of the appended claims. 

1. An adjustable shaft apparatus, comprising: (a) a first hollow shaft portion; (b) a second hollow shaft configured for axial operative alignment with said first shaft portion; and (c) a releasable locking assembly mounted within and connecting said first and second shaft portions in axial alignment, said locking assembly being arranged and configured to respond to relative twisting motion between said first and second shaft portions about said axis, to selectively fix the angular orientations of said first and second shaft portions relative to one another, to any desired angular positions.
 2. An adjustable shaft apparatus as recited in claim 1, wherein said releasable locking assembly contains no threaded operative parts.
 3. An adjustable shaft apparatus as recited in claim 1, wherein said releasable locking assembly is operable to fixedly lock the first and second shaft portions together when the shafts are relatively twisted in first angular directions about said axis, and is operable to release the locking condition and allow free angular relative motion between said first and second shaft portions when the shafts are relatively twisted in second angular directions, opposite to said first angular directions, about said axis.
 4. An adjustable shaft apparatus as recited in claim 3, wherein the amount of angular rotation of either said first or said second shaft portions about said axis in order to fixedly lock the shaft portions together when relatively twisted in said first angular directions, is less than about 180°.
 5. An adjustable shaft apparatus as recited in claim 3, wherein the amount of angular rotation of either said first or said second shaft portions about said axis in order to fixedly lock the shaft portions together when relatively twisted in said first angular directions, is less than about 90°.
 6. An adjustable shaft apparatus as recited in claim 3, wherein the amount of angular rotation of either said first or said second shaft portions about said axis in order to fixedly lock the shaft portions together when relatively twisted in said first angular directions, is less than about 45°.
 7. An adjustable shaft apparatus as recited in claim 1, wherein said releasable locking assembly further includes a shaft extension insert fixedly secured to the first shaft portion and longitudinally releasably securable to said second shaft portion; wherein said releasable locking assembly is operable to selectively change the distance between adjacent ends of said first and second shaft portions up to an operative length of said extension insert.
 8. An adjustable shaft apparatus as recited in claim 7, wherein said releasable locking assembly is operable to lock the longitudinal position of said shaft extension relative to said second shaft portion at any position along the operative length of said shaft extension.
 9. An adjustable shaft apparatus as recited in claim 1, wherein said first and second shaft portions are configured for cooperative longitudinal mating connection with one another so as to form an extendable composite shaft configuration; wherein said releasable locking assembly is fixedly secured to the first shaft portion and longitudinally releasably secured to said second shaft portion; wherein said releasable locking apparatus is operable to selectively lock the longitudinal positions of said shaft portions relative to one another.
 10. An adjustable kayak paddle, comprising: (a) a shaft having first and second ends and being separable near its longitudinal center; (b) paddle blades fixedly attachable to said first and second shaft ends; and (c) a releasable locking assembly mounted within said shaft and bridging the separable portion thereof; said locking assembly being operable in response to relative twisting motion between the separable shaft segments about the shaft axis to fix the angular orientations of said shaft segments and attached paddle blades about said axis, at any desired angular positions.
 11. The adjustable kayak paddle of claim 10, wherein said releasable locking assembly is further operable in response to said relative twisting motion between the separable shaft segments to adjustably fix the length of said shaft at an infinite number of lengths within an adjustment range.
 12. A shaft adjustment locking apparatus of a type being sized and configured to be entirely operatively inserted within first and second joinable shaft segments to be controlled, and containing no operable threaded parts, comprising: (a) a first portion configured for fixed mounting within the first shaft; (b) a second portion configured for slidable movement within and relative to said second shaft, comprising: (i) a cam member mounted for movement with said first portion; and (ii) a cam follower rotatably mounted on said cam member and engageable with an inner surface of said second shaft, for selectively frictionally engaging said inner surface of said second shaft in response to rotation of said cam follower relative to said cam member.
 13. A shaft adjustment locking apparatus as recited in claim 12, wherein said cam member includes a cam surface eccentrically oriented with respect to a longitudinal axis of said first and second shafts. 